Libyan protesters and militiamen stormed the headquarters of the election commission in the eastern city of Benghazi on Sunday, setting voting slips on fire, a militia commander said, a week before the country holds its first general election in nearly five decades.

In southern Libya, a leader of the Tabu tribe threatened to boycott the election if the government does not withdraw its forces and tanks from the desert city of Kufra where clashes have killed dozens.

The violence and calls for boycotts threaten to tarnish the process of electing a 200-member assembly to form a government and oversee writing of a constitution.

In Benghazi, where the revolt that unseated Muammar Gaddafi began last year, Fadallah Haroun, commander of a former rebel militia, said he joined protesters in the attack on the election commission. This came after the ruling transitional council in Tripoli turned down demands to give the east an equal share of seats in the assembly. He said two other cities in eastern Libya have witnessed similar incidents.

"We want justice," Haroun said. "We lost tens of thousands of martyrs because we want a state built on justice, law and equal rights."

As the situation stands, Tripoli and western Libya would have 102 seats, while the oil-rich east's share would be 60. The rest would go to the sparsely populated south. Eastern leaders say this leaves them with no influence over drafting of the constitution.

The 7 July vote will be the country's first nationwide election since the 1960s. Gaddafi, who ruled for 42 years, banned political parties and elections.

Benghazi, the largest city in eastern Libya, suffered marginalisation under the Gaddafi regime. In March, leaders and commanders held a meeting to discuss plans for semi-autonomous rule in the east. The transitional council accused them of trying to split the country into mini-states.

In the south, Tabu leader Issa Abdel-Majid told Associated Press his tribe, which is of African origin, will not vote if government troops continue to deploy tanks, anti-aircraft missiles and snipers against Tabu fighters battling a rival Arab tribe, Zwia, in Kufra. He said dozens of Tabu civilians have been killed and homes destroyed in the clashes.

Neither government officials nor groups such as the Red Cross, which has previously helped evacuate the wounded from Kufra, could confirm the number of people killed in the latest round of fighting over the past week.

Armed clashes have erupted several times over the last few months, leaving dozens killed and injured, mainly among the Tabu, the original inhabitants of southern Libya who were heavily suppressed under Gaddafi.

Abdel-Majid said his tribe wants an international peacekeeping force to be stationed in Kufra and for Tabu representatives to be given seats in the country's cabinet. "If our demands are not met, we are boycotting the elections," he said.

Amnesty International's Libya researcher Diana el-Tahawy said the government failed to send a fact-finding mission to Kufra to determine who was behind attacks and compensate victims after clashes killed more than 100 in February. Unresolved disputes have boiled over since. "The [government] is either unwilling or unable to control these militias," she said.